Although scientists anticipated years ago that automated machines, or robots, could be designed to perform myriad tasks in the place of humans, and the general expectation that robots one day should perform the majority of mundane physical tasks has become ubiquitous, the realization of this vision has been slow to develop. Even with the prominence of the modern microprocessor, many difficulties have yet to be overcome before robotic machines will be capable of performing common tasks easily performed by humans. Nevertheless, significant advancements have been made in this area of technology, particularly with regards to application-specific robotic machines developed to perform specialized tasks in mass-production or high-precision manufacturing processes.
While stationary robots with multi-jointed appendages may be programmed to execute specific movements within a limited area, or such robots may be transported about an extended area by a gantry, the development of free-roaming robotic machines capable of navigating their way over a variety of different surfaces has proven more difficult. Mobile robots depend on the advancement of technology in the area of automatic guided vehicles (AGVs). A number of navigation schemes for such vehicles have met with limited success, based on technologies such as gyroscopes, magnetic sensors, wheel encoders, radio transponder sensors, the Global Positioning System (GPS), or laser reflectors.
Unfortunately, each of these systems fails to provide a cost effective solution with the required accuracy and response time. For example, some existing systems present response-time difficulties due to the complexity of the required real-time calculations. These difficulties are compounded when three-dimensional, as opposed to two-dimensional, navigation and control is contemplated. Other systems do not provide sufficient accuracy for applications that require increased precision, such as certain manufacturing processes. Furthermore, existing positioning and navigation systems may be cost prohibitive.
Accordingly, it is desirable to provide a method and apparatus for the navigation and control of a vehicle that provides a high degree of positional accuracy, while limiting the quantity and complexity of real-time calculations necessary to determine and correct the position of the vehicle, in two-dimensions as well as in three-dimensions, all without incurring excessive costs.